We hear a lot about SDN lately. It is getting almost as pervasive a buzzword as “cloud”.
What is SDN? Software-defined networking is a new paradigm for server network traffic control that allows network administrators to manage network services through a lower level of functionality. That is by breaking up the system that makes decisions about where traffic is sent (the control plane) from the underlying systems that forward traffic to the selected destination (the data plane).
In a nutshell, it is basically a way to simplify network management by removing the control of network traffic from the Ethernet Layer 3 switching to the Application Layer 7. Think of a traditional network: Layer 7 applications hosted on servers and clients (and other devices) are connected to an Ethernet core and edge topology by those servers. The Ethernet core and edge is then configured for optimum traffic transport to and from those Layer 7 applications, with resiliency against failure . To put it simply think of it as the servers are the parking garages, which deliver the cars to the Layer 3 core; which in turn is the traffic cop deciding the most efficient route for the cars leaving the server to get to the other servers. The Layer 3 edge switches in turn are the freeways to get to the other servers. With SDN, the server becomes the traffic cop itself, and directs the traffic directly onto the freeways.
An open source protocol (OpenFlow) will allow network administrators to dynamically configure applications and network traffic changes on SDN controllers instead of a Layer 3 core. In addition to faster configuration times, it also allows for centralized management, since network flow will be flattened , appearing to applications and policy engines as a single, logical switch. It is a goal to have automated SDN programs for network and applications management, which administrators can write themselves because the programs will not depend on proprietary software.
There is a networking industry supported open source group known as the OpenDaylight Project that was formed in April of 2013. This group’s purpose is to facilitate an open source framework to accelerate the adoption of SDN as well as foster new innovation around it’s functionality.
As noted, it is built around an open-source protocol , known as OpenFlow, with industry giants such as Cisco, Brocade, Avaya, Citrix, Ericsson, HP, IBM, Juniper Networks, Microsoft, NEC, Nuage Networks, PLUMgrid, Red Hat , VMware as well as newcomers Arista Networks, and Big Switch Networks committed to providing software and engineering resources for the project. One will note that only Brocade, Cisco, Avaya, Juniper and HP are traditional networking companies.
One of the reasons the traditional networking players are involved is obviously to have a hand in developing OpenDaylight’s open source framework that will define the future of an open source SDN platform. This will be crucial to sustaining the business models of the traditional players. The first code from the OpenDaylight Project, named Hydrogen, was released in February 2014. Industry reaction to the OpenDaylight Project has been a mixed bag, while reaction to the goals of the open architecture/ administration of the Linux Foundation have been mostly positive.